FR3005585A1 - PARTICLE AGGREGATE REMOVING RADIOACTIVE MATERIAL, PROCESS FOR MANUFACTURING AND METHOD OF REMOVING CONTAMINANTS - Google Patents

Abstract

An aggregate of radioactive material extraction particles is created in which two or more radioactive material extraction particles comprising magnetic particles and a radioactive material adsorption component are associated, wherein a pore volume in the aggregate is greater than or equal to 0.5 ml / g and less than or equal to 5.0 ml / g, and the pore volume represents a cumulative value obtained by a process by pressurization in mercury.

Description

The present invention relates to an aggregate of radioactive material extraction particles and to its production process, as well as to an extraction process. of contaminant using the aggregate of radioactive material extraction particles.

In the prior art, when a radioactive material is contained in incinerated light ash produced at a general waste incineration site, etc., the radioactive material is a subject to environmental regulation and its treatment presents a problem. The isotopes 134Cs and 137Cs, and more particularly 137Cs, as radioactive materials, have a long half-life of 30.2 years, thus implying a problem in that a significant part remains, even 10 years after its generation. Therefore, the contaminant involves a risk of compromising environment and ecosystem on a long-term basis. Therefore, it is required to extract the contaminant from the environment.

However, a relatively large accumulation of radioactive cesium is present in incinerated fine fly ash having a particle size of 20 to 30 gm produced at the general waste incineration site, etc., and according to known public documents, etc. , the accumulation of cesium sometimes reaches several tens of thousands Bq / kg. In view of such circumstances, one of the inventors of the present invention has described the patent document 1 in which a decontaminating agent is intended to extract radioactive cesium. The decontaminating agent of Patent Document 1 makes it possible to extract radioactive cesium effectively from a liquid containing a radioactive material. In addition, patent document 1 discloses a method of separating and extracting radioactive cesium without directly affecting the decontamination agent which captures the radioactive cesium. As a prior art patent document the patent document 1 is the patent publication No.4932054. As a result of investigation of the decontaminating agent, the inventors of the present invention have discovered that the response to a magnet is substantially improved if the water content is extracted from the decontaminant using a method such as drying, and two or more particles contained in the decontaminating agent are combined to form an aggregate. The inventors of the present invention have also discovered that a suspended substance and the aggregate of the decontaminating agent can be easily separated by forming the aggregate of the decontamination agent even if the liquid to be treated is in a paste state because of the suspended material, and, therefore, if the radioactive cesium is separated from the suspended material in the pulp and is absorbed by the decontamination reagent, a substantial reduction of cesium-containing waste material radioactive can be obtained. However, the inventors of the present invention have also discovered that a substantial volumetric shrinkage occurs at the time of drying if the water content is extracted from the decontaminating agent in a slab state by drying. so as to be shaped into an aggregate, wherein the decontaminating agent is in a dehydrated slab state having a high water content. It has also been discovered that, due to the large volumetric shrinkage, the primary particles of the decontaminating agent adhere to one another, leading to the formation of a firm aggregate with a high density, and it occurs. sometimes a case in which the permeation of a liquid to be treated containing water-soluble cesium is prevented in the aggregate. When the permeation of the liquid to be treated containing the water-soluble cesium is prevented in the aggregate, there is a problem of reducing the decontamination effect. In the above circumstances, the present invention is created, and an object of the present invention is to create the aggregate of the radioactive material and a method of producing the same, as well as a method of extracting the radioactive material using the aggregate of radioactive material extraction particles. In summary of the invention, for the purpose of solving the problem mentioned above, the inventors of the present invention have studied a form of an aggregate of radioactive material extraction particles, and as a result of significant efforts, it has It has been discovered that a substantial shrinkage occurs at the time of drying when a decontaminant in a slab state is heated or dried naturally, and because of such shrinkage, the permeation of the liquid to be treated into the aggregate of Extraction particles of radioactive material is difficult. On the basis of such knowledge, it has also been discovered that excellent decontamination capabilities are obtained even in a short time from the start of a radioactive material extraction operation, with a structure as follows. : pores are formed in the aggregate of radioactive material extraction particles when the aggregate of radioactive material extraction particles is formed, so that the permeation of a liquid to be treated in the aggregate is easily assured. The present invention is thus created. That is, for the purpose of solving the aforementioned problem, a first aspect of the invention creates an aggregate of radioactive material extraction particles in which two or more radioactive material extraction particles comprising magnetic particles and a component of adsorption of radioactive material are associated, wherein a pore volume in the aggregate is greater than or equal to 0.5 ml / g and less than or equal to 5.0 ml / g, and the pore volume represents a value Cumulatively obtained by a process by pressurization in mercury. A second aspect of the invention provides an aggregate of radioactive material extraction particles in which two or more radioactive material extraction particles comprising magnetic particles and a radioactive material adsorption component are associated, wherein a value of cumulative amount of pore volume in the aggregate is greater than or equal to 0.3 ml / g and less than or equal to 3.0 ml / g in a range in which the diameter of the pore volume in the aggregate is greater than at an average particle size of each magnetic particle which is a source of radioactive material extraction particles, and less than an average particle size of the aggregate, wherein the pore volume represents a cumulative value obtained by a process by pressurizing in mercury. A third aspect of the invention provides an aggregate of radioactive material extracting particles according to the first or second aspect of the invention, wherein a specific surface area of the aggregate obtained by the BET method (from Brunauer, Emmett et al. Teller) is greater than or equal to 1 m 2 / g and less than or equal to 400 m 2 / g, in which the BET method is the process of not performing a de-aeration operation. A fourth aspect of the invention creates an aggregate of radioactive material extracting particles according to any one of the first to third aspects of the invention, wherein the average particle size (D50 diameter) is greater than or equal to 0.1 μm and less than or equal to at 100 i.tm. A fifth aspect of the invention provides an aggregate of radioactive material extraction particles according to any one of the first to fourth aspects of the invention, wherein the radioactive material adsorption component is a radioactive material adsorption component. ferrocyanide comprising at least one type of transition metal elements or group 12 elements. A sixth aspect of the invention provides a method for producing an aggregate of radioactive material extraction particles, comprising the step of drying a pulp of a spray drying decontamination agent, wherein a metal salt of ferrocyanide compound is formed as a radioactive material extracting substance on a surface of a magnetic particle with a layer of polymer or monomer formed on its surface by a wet process. A seventh aspect of the invention provides a method for producing an aggregate of radioactive material extracting particles according to the sixth aspect of the invention, comprising the steps of: forming the polymer or monomer layer on the magnetic particle adding a polymer or monomer having cationic properties to the pulp in which the magnetic particles are dispersed; and forming a decontamination component on a coating layer and / or in the coating layer of the magnetic particles bonded to a coating layer by adding the ferrocyanide compound having at least one type of the transition metal elements or group 12 elements, to the paste of the magnetic particles bonded to a coating layer. An eighth aspect of the invention provides a method of producing an aggregate of radioactive material extracting particles according to the sixth or seventh aspect of the invention, wherein the spray drying is carried out by a drier. spray. A ninth aspect of the invention provides a process for extracting a contaminant, wherein the aggregate of radioactive material extracting particles according to any one of the first to fifth aspects of the invention is dispersed in a liquid to be treated containing a contaminant, such that the contaminant is displaced to the radioactive material extraction particle aggregate. A tenth aspect of the invention provides a method of extracting a contaminant according to the ninth aspect of the invention, wherein the decontamination material is radioactive cesium and / or radioactive thallium. The aggregate of radioactive material extraction particles of the present invention makes it possible to accelerate a permeation of the treatment liquid in a liquid to be treated containing a contaminant, and makes it possible to increase a specific surface area of a portion of absorption of radioactive material by aggregate by binding a radioactive material adsorption component to a surface layer of the radioactive material extracting particles constituting the aggregate. Therefore, the contaminant in the liquid to be treated can be extracted efficiently in a short time. A brief description of the drawings will now be given below. Figure 1 is a scanning electron microscope (SEM) image ((A) is an image with a magnification factor of 500, and (B) is an image with a magnification factor of 5000) of decontamination agent according to an example 1. Fig. 2 is a graph showing a particle size distribution of the decontamination agent aggregates according to Examples 1, 2, and a comparative example. Fig. 3 is an SEM image ((A) is an image with a magnification factor of 500, and (B) is an image with a magnification factor of 20000) of decontamination agent aggregates according to Example 2 Fig. 4 is an SEM image ((A) is an image with a magnification factor of 500, and (B) is an image with a magnification factor of 20000) decontamination agent aggregates according to an example. 3. Figure 5 is an SEM image (an image with a magnification factor of 15000) of a sectional face of a decontaminating agent aggregate according to Example 3. Figure 6 is an image of SEM ((A) is an image with a magnification factor of 500, and (B) is an image with a magnification factor of 50000) of decontamination agent aggregates according to Comparative Example 1. A detailed description of the invention will now be given below. An aggregate of radioactive material extracting particles and a production method thereof according to the present invention will be described hereinafter in detail, with in order (1) the aggregate of extraction particles. radioactive material, (2) the method of producing the radioactive material extracting aggregate, and (3) the method of extracting a contaminant from a liquid to be treated using a radioactive material extractant. decontamination of radioactive material. (1) Radioactive Material Extraction Particle Aggregate The radioactive material extraction particle aggregate according to the present invention is the aggregate consisting of two or more radioactive material extraction particles comprising magnetic particles and a component adsorption (absorption) of radioactive material, wherein pores are formed in the aggregate. More specifically, the aggregate has a structure in which a coating layer based on the radioactive material adsorption (absorption) component is formed on at least a portion of the surface of at least a portion of the magnetic particles.

Explanations will be given hereinafter, in the order <1> magnetic particles, <2> the adsorption component (absorption) of radioactive material, <3> the particles of extraction of radioactive material, and < 4> the aggregate of radioactive material extraction particles. <1> Magnetic particles The magnetic particles as the nucleus of the radioactive material extraction particles according to the present invention are the magnetic particles based on metallic iron and / or iron alloy. The iron alloy is obtained by adding one or more of cobalt and nickel, etc., which are transition metal elements other than iron, iron to make the adjustment, and / or adding one or more types of selected elements from silicon and aluminum so as to impart some stability to the oxidation. Magnetic particles are magnetic particles having a mean primary particle size of 10 to 500 nm, preferably 10 to 400 nm, and more preferably 30 to 300 nm.

If the average primary particle size is greater than or equal to 10 nm, the magnetic particles have sufficient magnetism and, preferably, the decontamination capabilities can be provided when the magnetic separation is carried out. In parallel, if the average primary particle size is less than or equal to 500 nm, the radioactive material extraction particles that can be dispersed in a liquid to be treated can be obtained when a decontamination operation is carried out, in view of the structure in which pores are formed in each radioactive material extraction particle as will be described later. The average primary particle size may be calculated as a mean value of diameters of 100 or more particles, obtained by confirming each particle shown by appropriate magnification, using, for example, a transmission electron microscope. The shape of the magnetic particle is not particularly limited, and when the magnetic particle is a needle-like particle, or a particle similar to the needle-shaped particle, it appears that a large porosity is ensured. during the formation of the aggregate by drying the magnetic particles, and this is preferable from a point of view of the present invention. When each magnetic particle has a needle shape, the average primary particle size mentioned above indicates "an average longitudinal axis length". <2> Adsorption (absorption) component of radioactive material The adsorption (absorption) component of radioactive material is present at least on part of the surface of the magnetic particles as previously described. Then, the adsorption (absorption) component of radioactive material is a monomer and / or polymer having cationic properties from a point of view of adhesion stability on the magnetic particle, and monomer and / or polymer having the cationic properties include a cesium adsorption component consisting of a ferrocyanide compound having at least one type of transition metal elements or group 12 elements (described in some cases as a "metal compound salt of 25"). ferrocyanide "in the present invention). (1) The polymer and monomer having cationic properties, and (2) the metal salt of ferrocyanide compound, will be described hereinafter. (1) Polymer and monomer having cationic properties The cationic monomers and polymers mentioned above are not particularly limited, if they are monomer and polymer having cationic properties, and if they are monomer and polymer having a group which is ionized to produce a cationic group. In addition, the cationic monomer and polymer may have the cationic properties of part of a main chain, or may have the cationic properties by a side chain substitution group linked to the main chain.

Further, when the cationic monomer is used, a vinyl monomer having a primary amino group, a vinyl monomer having a secondary amino group, a vinyl monomer having a tertiary amino group, and a vinyl monomer having a quaternary ammonium group, etc. , can be used.

In addition, when the cationic polymer is used, the cationic polymer adding cationic properties to the synthetic polymer can be used, or the cationic polymer adding cationic properties to the natural polymer or polymer derived from microorganism such as cationic cellulose, the cationic starch, cationic dextran, cationic guar gum, and cationic chitosan, etc. may be used. The cationic monomers and polymers mentioned above may be used alone, or may be used in a mixture. (2) Ferrocyanide compound metal salt The ferrocyanide compound containing at least one type of the transition metal elements or group 12 elements comprises, for example, a substance having adsorption or cesium exchange performance, such as iron ferrocyanide (Prussian blue), nickel ferrocyanide, copper ferrocyanide, cobalt ferrocyanide, and zinc ferrocyanide, etc. Above all, when applied to fly ash, ferrocyanide Nickel is preferable from the point of view of the alkalinity of the liquid to be treated which becomes high. Iron ferrocyanide inexpensive is also preferable, under a condition in which the pH can be adjusted by adding hydrochloric acid in the liquid to be treated. <3> Radioactive Material Extraction Particles The radioactive material extraction particles of the present invention have a structure such that at least a portion of the surface of the magnetic particle mentioned above is coated with the monomer and / or polymer having cationic properties, wherein the metal salt of iron ferrocyanide compound is present on the surface and / or inside (surface layer portion) of the coating layer.

The amount of the monomer and / or polymer having cationic properties, which is present on the surface of the magnetic particle as a coating layer, is less than or equal to 10% by weight, preferably less than or equal to 5% by mass, and more preferably, less than or equal to 2% by weight in the form of a pure solid part contained in a treatment liquid used for the coating, in terms of the monomer and / or polymer. By adjusting the solid portion to 10% or less, the increase in viscosity can be prevented and, therefore, the coating above the magnetic particle is preferably uniform. The metal salt of ferrocyanide compound as a decontamination component which is present on the surface of the radioactive material extraction particle, is a compound of ferrocyanide ion and transition metals or group 12 elements, etc. For example, potassium nickel ferrocyanide, nickel ferrocyanide, iron ferrocyanide (Prussian blue), cobalt ferrocyanide, and zinc ferrocyanide, etc., may be mentioned. In particular, the metal salt of ferrocyanide compound containing nickel in its structure is preferable. A present amount of the ferrocyanide compound metal salt can be calculated by quantitatively measuring a quantity of transition metals, etc., of the ferrocyanide compound metal salt (excluding iron ferrocyanide) by ICP emission spectrometry and X-ray fluorescence analysis, and conversion of the amount obtained to the present amount of ferrocyanide compound metal salt. More readily, the amount of the ferrocyanide compound metal salt can be calculated by a simple comparison of an amount of ferrocyanide compound metal salt calculated from the added amounts of a source of ferrocyanide material (aqueous solution of ferrocyanide compound). potassium ferrocyanide or sodium ferrocyanide) and a transition metal source, etc., and a weight of magnetic powder added initially. Preferably, the amount of the metal salt of ferrocyanide compound in the radioactive material extracting particles is set to not be greater than 5 times the weight of the magnetic powders, so that the metal salt of the compound Ferrocyanide can be easily separated from the suspended substance when magnetically separated. In addition, the amount formed of the ferrocyanide compound metal salt is preferably defined to be greater than 0.1 times the weight of the magnetic powder, considering the operational character and cost required for the operation of the decontamination. <4> Radioactive Material Extraction Particle Aggregate The radioactive material extraction particle aggregate of the present invention is formed by combining two or more radioactive material extraction particles mentioned above, and has a structure in which wherein pores are open outwardly on the surface of the aggregate, and the pores are also open to the interior of the aggregate as a gap between the radioactive material removal particles. That is, the aggregate is not formed with the carrier-supported radioactive material extraction particles, etc., but formed by the combination of two or more radioactive material extraction particles, know, in such a way that the pores open outwards and are present in the aggregate. By having such a sponge-shaped structure, the permeation of the liquid to be treated is easily ensured in the aggregate of radioactive material extraction particles. In addition, by binding the radioactive material adsorption component on a surface layer of the radioactive material extracting particles, a reaction zone of the radioactive material adsorption portion per aggregate can be increased. As a result, the radioactive material can be extracted in a short time.

In the aggregate of radioactive material extracting particles of the present invention, the pore volume measured by the process by pressurizing mercury is greater than or equal to 0.5 ml / g, preferably , greater than or equal to 0.6 ml / g, more preferably greater than or equal to 0.7 ml / g and less than or equal to 5.0 ml / g as upper limit, preferably less than or equal to 4.0 ml / g, and more preferably, less than or equal to 3.0 ml / g.

If the pore volume is greater than or equal to 0.5 ml / g, the aggregate of radioactive material extraction particles has sufficient interstices in its structure, and the permeation of the liquid to be treated is easily ensured in the aggregate. . In addition, since the reaction zone of the radioactive material adsorption component per aggregate is large, the radioactive material can be easily extracted in a short time. At the same time, if the pore volume is less than or equal to 5.0 ml / g, a sufficient amount of the radioactive material extracting particles is present in its structure, and this is preferable. The value of the specific surface area of each radioactive material extraction particle of the present invention obtained by the BET method is greater than or equal to 1 m 2 / g, less than or equal to 400 m 2 / g, preferably greater than or equal to equal to 5 m 2 / g, more preferably greater than or equal to 10 m 2 / g and less than or equal to 350 m 2 / g If the specific surface area is greater than or equal to 1 m 2 / g, a contact surface with the treatment liquid can be assured, and extraction efficiency can be ensured. In parallel, if the specific surface area is less than or equal to 400 m 2 / g, the particle size of the radioactive material extraction particle is ensured and, consequently, the simultaneous precipitation with an object to be treated does not occur, and this is preferable. However, the value of the specific surface area obtained by the BET method is the value measured by the BET method without performing a de-aeration operation which is generally carried out, because there is a risk that the salt metal of ferrocyanide compound is thermally decomposed.

Further, when the measurement of the cumulative value of the pore volume by the pressurized process in mercury is carried out on the aggregate of radioactive material extraction particles of the present invention, the Effective area of each pore can be measured by mercury. The effective surface area of the pores by the mercury pressurized process has the effective surface area of the pores in a range in which the mercury can enter by pressure, thus allowing a relatively large surface irregular state to be known. Namely, by calculating the "pore effective area by the mercury pressure / specific surface area obtained by the BET method" ratio, a relatively large pore presence ratio on the pores of the entire body of the aggregate, can be known. According to the review made by the inventors of the present invention, it has been discovered that the contaminant can be extracted in a short time, when the aforementioned presence ratio is greater than or equal to 39%. (2) Method for producing the radioactive material extraction particle aggregate Explanations will be given for the method of producing the radioactive material extract particle aggregate according to the present invention, with in order <1> the source powder containing magnetic particles, <2> the formation of the coating layer on the magnetic particle, <3> the formation of a capture layer of radioactive material on the magnetic particle, <4 > the production of the radioactive material (de) contamination agent by forming the radioactive material extraction particles into an aggregate. <1> Source Powder Containing Magnetic Particles A source powder for producing the radioactive material extracting particles of the present invention is preferably a powder containing metal iron or alloy particles. iron (such as cobalt and nickel which are other transition metals in order to adjust the magnetic properties, and such as silicon and aluminum, etc., in order to adjust the composition or to communicate a certain stability to oxidation). However, the source powder is not particularly limited if it is a powder with a certain magnetism. As described above, the average primary particle size of the magnetic particle contained in the source powder is 10 to 500 nm, preferably 10 to 400 nm, and more preferably 30 to 300 nm. nm. In addition, a coercive force of the magnetic particles is 100 to 20000, and preferably about 500 to 20000. <2> Formation of the coating layer on the magnetic particle The aforementioned source powder is added in pure water and stirred, thereby obtaining the source powder paste. The stirring can be carried out so as to disperse the source powder without sedimentation. Ammonia or an aqueous solution of sodium hydroxide is added to the resulting source powder paste so that the alkalinity of the source powder paste is adjusted to thereby impart anionic properties to the surface of the source powder paste. a magnetic body. The above-mentioned monomer and / or polymer having cationic properties are added to the source powder paste whose alkalinity is adjusted, thereby forming the coating layer on the surface of the magnetic particles due to the cationic properties of the monomers and or polymer. It is not necessary that agitation in this step be strong, and agitation may be able to disperse the source powder (magnetic particles) without sedimentation. In addition, even in a case of normal agitation, the magnetic particles can be coated by sonication according to a level of treatment. An added quantity of the monomer and / or polymer having cationic properties as described above is less than or equal to 10% by weight, preferably less than or equal to 5% by weight, and more preferably less than or equal to 2% by weight. mass relative to the weight of the source powder, as a pure solid part in terms of the monomer and / or polymer. By adjusting the solid portion to less than or equal to 10%, excessively high viscosity is prevented, and a monomer and / or polymer coating layer on the magnetic particles is preferably uniform. After the coating layer has been formed on the surface of the magnetic particles by the monomer and / or the polymer, the monomer and / or the polymer not completely covering the magnetic particles remain in some cases in the powder paste of source. When the monomer and / or polymer remain in the source powder slurry, the magnetic particles are preferably separated from the remaining polymer and / or monomer by separating the magnetic particles from the source powder slurry after reaction. A separation process involves magnetic separation, natural sedimentation, and centrifugal separation, etc. Among these, natural sedimentation and centrifugal separation without requiring the application of a magnetic field, are appropriate in that subsequent steps are thus not affected. It may be noted that when the amount of monomer and / or polymer remaining is low in the source powder slurry, the separation step may be omitted. Whether or not the surface of the magnetic particles is coated with the monomer and / or polymer by the aforementioned series of operations can be confirmed by measuring a zeta potential on the magnetic particles or by taking and drying the particles. part of the magnetic particles, and measures a carbon content in the magnetic particle drying body. <3> Formation of a Radioactive Material Capture Layer on the Magnetic Particles When the separation step is provided, pure water is added to the magnetic particles bound to a monomer and / or polymer coating layer having cationic properties on the surface of the magnetic particles, so as to turn them into paste. The ferrocyanide compounds and metal components comprising at least one type of transition metals such as Ni, Fe, Co, Cu, and Zn, and Group 12 elements, are added in this order or in reverse order to the pulp. of magnetic particles bonded to a coating layer, thereby forming a decontamination component on the coating layer and / or the coating layer of the magnetic particles bonded to a coating layer. The ferrocyanide compound and the metal compound are preferably respectively in a state of water-soluble substances when added to the slurry of the magnetic particles bound to a coating layer. It is required that the magnetic particles be coated effectively in contact with a substance produced in the step of adding / coating the ferrocyanide compound and the transition metals or group 12 elements. Therefore, the magnetic particles bound to a coating layer, are dispersed while adding a high shear stress to the paste of the magnetic particles bonded to a coating layer, using a dispersion machine having a high shear force. With regard to the high shear force dispersing machine, the devices "TKhomomixer (proprietary mixer)" (trademark) by Primix Corp., and "Ultra-Turrax" (trademark) by IKA Corp., can be cited as stator turbine type mixers, and "TKMicollider", "TKhomomicline" (trademark) grinders, and "TKhighline" (trademark) grinder by Primix Corp., and a static mixer (trademark filed), a high pressure (trade mark) micro-reactor, and a high pressure homogenizer (trade mark), etc., by Noritake Co., Ltd., can be cited as colloid mills. The high / low level of the shear force can be evaluated by a blade peripheral speed of a stirring blade, when a device comprises a stirring blade. According to the present invention, "high shear stress" occurs when the blade peripheral speed is greater than or equal to 5.0 (m / s), preferably greater than or equal to 7.5 (m / s) and, more preferably, greater than or equal to 10.0 (m / s). If the blade peripheral speed is greater than or equal to 5.0 (m / s), sufficient shear stress can be added to the solution, and the ferrocyanide compound metal salt can be sufficiently bonded to the coating layer. As a result, a sufficient cesium adsorption value can preferably be ensured over the radioactive material extracting particles produced, and, therefore, extraction performance is ensured upon removal of the contaminant in the process. liquid to be treated.

In addition, by adding sufficient shear stress, the ferrocyanide compound metal salt can be strongly adhered to the coating layer. If the metal salt of ferrocyanide compound is strongly adhered to the coating layer, there is no possibility that the ferrocyanide compound containing radioactive cesium will peel off the surface of the radioactive material extraction particles, when the shaking operation is performed together with the liquid to be treated, using the radioactive material extraction particles. Since the metal salt of ferrocyanide compound containing radioactive cesium is not peeled off the surface of the radioactive material extraction particle, the contaminant in the liquid to be treated can preferably be efficiently extracted by separation. Magnetic material subsequently used, and a situation in which a cyanide compound remains in the liquid to be treated may preferably be prevented. The blade peripheral speed mentioned above can be calculated by (perimeter ratio / diameter (pi) x turbine blade diameter (m) x number of revolutions of agitation (rotational speed) for 1 second). For example, if the diameter of the turbine blade is 3.0 cm (0.03 m), and the number of revolutions of the agitation is 8000 rpm, the number of revolutions per second is 133, 3 t / s, and the blade peripheral speed is 12.57 (m / s). In addition, in order to obtain a stronger adhesion between the coating layer and the ferrocyanide compound metal salt, the magnetic particle paste and the solution of the ferrocyanide compound and the metal compound can be mixed with one another. the other, using, for example, a micro-mixer or an ultimate mixer. Such an operation is preferable because the separation of the ferrocyanide compound metal salt can be suppressed even if the radioactive material extracting particles of the present invention are stored in a pasty state. <4> Production of the decontaminant of radioactive material by forming the particles of extraction of radioactive material into an aggregate The water content is extracted from the pulp containing the particles of extraction of radioactive material so that the particles radioactive material are formed into an aggregate to thereby produce the radioactive material decontamination agent. As a method of extracting the water content of the pulp containing the radioactive material extracting particles, the method of forming the aggregate without allowing the appearance of excessive shrinkage while performing the drying operation, is preferably used. That is, for the purpose of forming the pores on the surface of the aggregate so that they open outwardly as well as the interstices between the material extraction particles. radioactive, a method of accelerating the extraction of the water content from the pulp containing the radioactive material extraction particles, is preferably used. The process includes, for example, a spray drying process or a freeze drying process etc. In particular, when the spray drying process is used, the aggregate of radioactive material extract particles is easily made. in a spherical form. If the aggregate of radioactive material extraction particles is made into a spherical shape, the fluidity of the radioactive material decontamination agent is increased, thus improving the feasibility in carrying out the decontamination operation. It is also preferable to make the aggregate of radioactive material extraction particles into a spherical form, from the point of view of increasing the reaction surface of the aggregate of radioactive material extraction particles, and increasing the decontamination efficiency.

When the spray drying process is used as a method of extracting the water content of the pulp containing the radioactive material removal particles, either of a disc type spray dryer and an injector type spray dryer can be used. For example, when the injector-type spray dryer is used, particle size, pore volume, surface area value, and effective area of each pore can be adjusted by the pulverization pressure of the pulp. , the feed speed of the dough, the concentration of the solid part of the dough, the drying temperature and the air volume / air velocity. Meanwhile, when the disc type spray dryer is used, the particle size, pore volume, surface area value, and effective area of each pore can be adjusted by the feed rate of - The dough, the concentration of the solid part of the dough, the drying temperature, the air volume / air velocity, and the rotational speed of the disc, etc. A heating temperature (inlet) of The spray dryer is set at a temperature which does not permit the decomposition of the ferrocyanide compound polymer, monomer, and metal salt present on the surface of the radioactive material removal particles. More specifically, the heating temperature is adjusted to a value of less than or equal to 300 ° C, preferably less than or equal to 275 ° C, and more preferably less than or equal to 250 ° C. (3) Process for extracting the contaminant from the liquid to be treated using the decontaminant of radioactive material Explanations are given concerning the process for extracting the contaminant from the liquid to be treated, using the agent decontamination of radioactive material of the present invention. Here, the incinerated fly ash paste containing radioactive cesium is used as the process liquid containing the radioactive material to describe the process of extracting radioactive cesium as a contaminant. First, the radioactive cesium is eluted in water by adding the incinerated fly ash containing the radioactive cesium and stirring it into a paste. If the incinerated fly ash is suspended in water, the pH of the liquid increases to a strongly alkaline state (about pH 12), thus improving the stability of the ferrocyanide compound metal salt contained in the decontaminant. of radioactive material. Therefore, the pH value of the dough is preferably adjusted using an acid such as hydrochloric acid. The pH value of the pulp is adjusted to a value of less than or equal to 11, preferably less than or equal to 10, and more preferably less than or equal to 9, thereby removing an isolation of the cyanide compound from the salt. metal of ferrocyanide compound. Therefore, the amount of the cyanide compound in the pulp after extraction of the radioactive cesium can be suppressed. The time required for agitation of the pulp after addition of fly ash incinerated in water is defined according to the content of radioactive cesium, and in particular, the content of the radioactive cesium dissolved in the water. However, the stirring time of the dough is set at 1 minute or more and preferably at 4 hours or more. The radioactive material decontamination agent of the present invention produced is added beforehand to the dough in which the incinerated fly ash is suspended, in a ratio of less than or equal to 10% by weight relative to the weight of the incinerated fly ash, and stirring is continued. The amount of the radioactive material decontamination agent added to the incinerated fly ash may also be greater than or equal to 10% by mass. However, if a value greater than or equal to 1% by weight of the radioactive decontaminating agent of the present invention is added, the radioactive cesium in the pulp can be sufficiently extracted. The time required for the addition treatment from the decontaminant of radioactive material, varies depending on the volume of the pulp to be treated, but the stirring can be carried out for 15 minutes or more and preferably , 30 minutes or more in a case where the dough is about 10 l. Then, the magnetic field is applied to the paste after treatment, and the decontaminant of radioactive material on which radioactive cesium is adsorbed, is adsorbed and selected. The magnetic field generator represented by a bar magnet which is always magnetized, or the magnetic field generator represented by an electromagnet capable of "producing / suppressing" the magnetic field by external positioning, for example, a superconducting magnet can be used. In addition, by using the magnetism generation control method from the outside, the radioactive material decontaminant capturing the radioactive material can be extracted by remote operation, and this is preferable. The decontaminating agent of extracted radioactive material is sealed in a conventional type tank having a structure that does not allow the leakage of radioactive material to the outside, and a precautionary treatment is applied to it in the form of a highly concentrated radioactive material.

The pulp after extraction of the decontaminant of radioactive material, passes through a filter, etc., and a solid / liquid separation is carried out, thereby extracting incinerated fly ash in suspension. The solid / liquid separation at this time can be carried out using any of the known methods. The separated and extracted water is circulated and reused as water content to further disperse the fly ash, so that a closed system can be formed for the process water. In parallel, the fly ash incinerated after purification, from which the radioactive cesium was extracted, are discarded as industrial waste by a device selected according to a residual amount of radioactivity, after confirmation of this residual amount.

The present invention will be specifically described with reference to examples. First, the explanations will be given regarding evaluation methods in the examples of the present invention and a comparative example, in the order of (1) the particle shape, (2) the average particle size and the distribution. particle size, (3) the specific surface area, (4) the pore volume measurement, (5) the actual density measurement, and (6) the cesium adsorption capacity confirmation method of the decontamination agent for radioactive material. (1) Particle shape The shape of the radioactive material extraction particle aggregate is confirmed from an image obtained by a field emission scanning electron microscope (S-4700 by HITACHI Corp.) with a magnification corresponding to a magnification factor of 60,000. (2) Average particle size and particle size distribution The average particle size and particle size distribution of the radioactive material extraction particle aggregate have were measured under a lens diameter condition: 200 mm, using a laser diffraction type particle size distribution measuring device (HELOS and RODOS-KF by SYMPATEC Corp.). (3) Surface area A value measured by a one-point process using a device-4-Sobe by Yuasa Ionics Co. Ltd., is used for the specific surface of the radioactive material extraction particle aggregate . However, the cyanide compound is adhered to this sample and there is a possibility that the cyanide compound decomposes due to the heating aeration operation and, therefore, the measurement is carried out without performing the operation. ventilation. (4) Pore Measurement The pore volume in the radioactive material extraction particle aggregate is measured using 0.3 to 0.5 g of a sample by the mercury pressurized process (device AutoPore IV 9500 by 10 Micromeritics Instrument Corporation). Parts excluding pores and void portions are extracted and confirmed, the pores and gap portions representing the space between the aggregates, which exhibit another remarkable feature and are considered to exist on the surface of the particulate extraction particles. radioactive material. A method of calculation will be described hereinafter with in the order <1> a lower limit value of a pore diameter, and <2> an upper limit value of the pore diameter. <1> Lower limit value of a pore diameter When each pore formed in the form of a gap between the radioactive material extraction particles is measured and confirmed by the transmission electron microscope, excluding pores which are present on the surface layer of the radioactive material extraction particle, a lower limit value of the pore diameter is confirmed in a range greater than the diameter of the magnetic particle (indicating a longitudinal axis length when the magnetic particle as a the source of radioactive material removal particles is needle shaped, and merely indicates the diameter of the magnetic particle as the source of radioactive material extraction particles hereinafter). However, when the data is intermittently collected by the mercury pressurized process, a value less than the diameter of the magnetic particle which is the source of the radioactive material removal particles is defined as the limit value. lower. For example, the microscope (or pore) volume is calculated, respectively, when the data have pore diameters of 204 nm, 243 nm, 270 nm, and 315 nm, and when an average diameter of the magnetic particle is 250 nm, which is the source of radioactive material extraction particles, a value in a case of 243 nm, is used as the lower limit value of the pore diameter. At the same time, the pressurized process in mercury is the process of introducing mercury into the pores and calculating the pore volume from a quantity of mercury and the added pressure in the case of the mercury. lower limit value of the pore diameter has the highest pressure value (therefore, the pore diameter is given as a final cumulative value, in parallel it is given as the lower limit value.) <2> Upper limit value of the diameter In order to exclude the gap parts that are present between the aggregates of the radioactive material extraction particles, the upper limit value of the pore diameter is defined in a range lower than the value of the average particle size ( D50) of the radioactive material extraction particle aggregate calculated by a type diffraction type particle size distribution measuring device. ser. However, similarly to the lower limit value, when the data are intermittently collected by the pressurized process in mercury, the value below the average particle size of the particulate extraction aggregate radioactive, is defined as the upper limit value. For example, the pore volume is calculated respectively when the data have pore diameters of 6.6 gm, 5.6 μm, 4.5 kim, and 3.8 Inn, and when D50 is equal to 5.3 gm the value in the case of 4.5 μm is used as the upper limit of the pore diameter. However, for the same reason as in the case of the lower limit value, the pressure added in the case of the upper limit value of the pore diameter has a lower pressure value (therefore, the pore diameter is given as a value integrated from this pressure value, in parallel, the pore diameter is given as the upper limit value.) -24- (5) Measurement of the actual density The actual specific value of the cesium decontamination agent The radioactive content is measured on the basis of a definition of "apparent porosity of refractory bricks, water absorption rate, and a density measurement method" described in JIS-R-2205 (1992). That is, a test sample is pulverized to a particle size passing entirely through any screen with an opening of 300 μm, and is then dried at a constant temperature of 110 ± 5 ° C. The dried sample is placed in a previously weighed pyknometer, with pure water added inside, and gently heated in a hot bath, with pure water poured to a benchmark line, and the total weights are measured to thereby calculate the actual density from each measurement value by the formula (1). Actual density = (P1 - P) / ((P1 - P) - (P3 - P2)) .... (1) in which P = mass of the pycnometer, P1 = mass in the case of the placement of the sample in the pycnometer, P2 = mass in the case of the pouring of the distilled water in the pycnometer to the reference line, and P3 = mass in the case of the introduction of the sample in the pycnometer and pouring the distilled water to the benchmark line. (6) Method for confirming the cesium adsorption capacity of the radioactive material decontamination agent The cesium adsorption capacity of the radioactive material extractant is confirmed by the formula (2) as follows the pH is adjusted to 10.7, and then cesium sulfate is dissolved in water to represent about 100 ppm of cesium, and a solution of 100 g after dissolution of the cesium sulfate is poured into a beaker of 200 l, and 0.1 g of decontamination powder prepared in the example, etc., is added inside, and the solution is stirred under speed conditions of 250 rpm for 30 minutes at room temperature, and a residual amount of cesium in the solution is obtained, the solution from which the decontaminating agent was extracted by magnetic separation of the solution after treatment, and the residual amount of cesium obtained is analyzed by spectroscopy. Atomic Emission Scanning ICP (Using High Frequency Inductive Coupled Plasma (IRIS / AP) Analysis Device) by Nippon Jarrell-Ash Co., Ltd.

Extraction rate (%) = (concentration before test - concentration after test) / concentration before test x 100 .... (2) In addition, 40 g of fly ash containing radioactive cesium and 400 ml of water are mixed and stirred for 24 hours, thereby separating the water-soluble cesium from the fly ash. Then, the pH is adjusted to 10.7 with hydrochloric acid while suspending the fly ash, and after a radiation dose has been measured, the decontamination agent is added internally in the ratio of 1/1000 to the weight of fly ash. Stirring is continued for 30 minutes after addition of the decontamination agent so that the radioactive cesium in the liquid is captured by the decontamination agent, and the decontamination agent after treatment is extracted by a magnet at neodymium. Then, the radiation dose after decontamination is measured, and after that, the decontamination capacity is calculated by: (radiation dose value before decontamination - radiation dose value after decontamination) / radiation dose value before decontamination x 100, thus to calculate the decontamination efficiency over a short period. In addition, the decontamination efficiency over a long period of time is also calculated, with a treatment time, after addition of the decontamination agent, set at 24 hours. With respect to decontamination capability, the radioactivity of the liquid is measured using an NaI scintillation detector (MUCHA by Raytest Corporation) to thereby obtain the radioactivity prior to decontamination. A specific amount of the decontaminant is added to the liquid after measurement, and the liquid is stirred for a specific time such that the cesium in the liquid is adsorbed on the decontaminant, and after the the decontamination agent was extracted by magnetic separation, the quantity extracted from the radioactivity is calculated by measuring the radioactivity of the liquid using the NaI scintillation detector as before the decontamination operation.

The distribution coefficient is the ratio of the fly ash before the decontamination operation to the radioactivity, which is the ratio to the radioactivity of the decontamination agent on which the radioactive cesium is distributed and extracted from the fly ash, when the radioactive cesium contained in the fly ash before the decontamination operation is distributed and extracted on the decontamination agent from the fly ash by the decontamination operation. Therefore, a larger value of the distribution coefficient shows that the radioactivity is moving towards the decontamination agent. More precisely, the distribution coefficient is calculated by the formula (3).

Coefficient of distribution (Kd) = [((radioactivity before treatment (Bq / kg) / 1000) - (radioactivity after treatment (Bq / kg) / 1000))] / radioactivity after treatment (Bq / kg) x (amount of added fly ash (g) / weight of the decontaminating agent (g))]. (3) For example 1, 540 g of pure water are poured into the 1000 ml volume beaker, and g of needle-shaped iron-cobalt alloy particles having an average longitudinal axis length of 235 nm (cobalt / iron = 3.0 atomic%) produced by DOWA Electronics Corporation are added to the interior, as a source powder containing the magnetic particles. Then, a fast emulsification and dispersing machine (TK MarkII homogenizer mixer by Primix Corp.) was used to emulsify and disperse the source powder at 8000 rpm for 30 minutes, thereby obtaining a paste. of dispersion of the source powder. 2.5 g of ammonia with a concentration of 21.3% are added to the source powder paste, thereby changing the pH to a basic pH, and then 0.50 g of PDDA (39%). a solid part of polydimethyldiallylammonium chloride) is added to the latter, so that the magnetic particles are dispersed and emulsified for 30 minutes at 8000 rpm by the aforementioned dispersion machine, thereby obtaining a paste of magnetic particles bonded to a PDDA coating layer. 160 g of aqueous potassium ferricyanide at 0.5 mol / l and 220 g of aqueous nickel sulphate at 0.49 mol / l are respectively added to the paste obtained from the magnetic particles bonded to a coating layer, and Emulsification is continued for 30 minutes at 8000 rpm with the aforementioned dispersion machine so that the nickel ferrocyanide adheres to the magnetic powder connected to the PDDA, thus making it possible to obtain the paste (approximately 10% of the solid part) containing the radioactive material extraction particles. The resulting paste containing the radioactive material extraction particles is charged into a static mixer and stirred for 5 minutes, thereby obtaining the paste. The stirred paste obtained is loaded into a micro-mixer, and the treatment is carried out so that the nickel ferrocyanide on the PDDA-coated magnetic powder adheres sufficiently to the PDDA coating layer and / or to the of the surface layer, thereby to obtain the paste (the stirring treatment by the static mixer and the coating treatment for the magnetic particles by the micro-mixer are in some cases described collectively as "MR treatment" in the present invention). The resulting slurry, after MR treatment, is spray-dried (drying condition: inlet temperature: 220 ° C., spray pressure: 35 mmHg, and pulp feed speed: 19% (about 200 ml / hr). )) by using an injector-type drier (Buchi Model B-290 Mini Spray Dryer) to thereby obtain the radioactive material extraction particle aggregate and thereby obtain the decontamination agent of Buchi. The data obtained are shown in Table 1. The form of the radioactive material decontamination agent obtained is observed using a SEM microscope (scanning electron microscope). The SEM image is shown in Fig. 1 (Fig. A is an image with a magnification factor of 500, and Fig. 2B is an image with a magnification factor of 5,000). From Figure 1, it is shown that the radioactive material extraction particle aggregate of Example 1 has a spherical shape and has an irregular structure on its surface. Next, the laser diffraction type particle size distribution measurement is performed on the radioactive material extraction particle aggregate, and a result thereof is plotted as "-" in FIG. Figure 2 is a graph on which the diameter of the aggregate is taken on the horizontal axis, and the cumulative particle size distribution is taken on the vertical axis. From the particle size distribution of the radioactive material extraction particle aggregate of Example 1 shown in Figure 2, it is then calculated that the average aggregate diameter (diameter D50) is 12. , 9 isin, the (diameter D90) is 23.5 1.irn, and the aggregate level less than or equal to 10 i.tm is 34.5%. In addition, the value of the specific surface area obtained by the BET method is equal to 63.9 m 2 / g, and the value of the actual density is 3.55. Next, the cumulative value of the calculated pore volume of the aggregate is 0.63 ml / g. In addition, the calculated cumulative pore volume is 0.37 ml / g in a range not greater than the average particle size of the radioactive material extraction aggregate of Example 1 (the pore diameter is equal to 17.64 μm in this example), and in a range not smaller than the average longitudinal axis length of the magnetic particles that form the source of radioactive material extraction particles (the pore diameter is 243 nm in this case). example). In addition, the integrated value of the effective pore area calculated by the process by pressurizing in mercury is 39.6 m 2 / g. In addition, a percentage value of the pore effective area by pressurization in mercury / specific surface area obtained by the BET method] is 62.0%.

The data obtained are shown in Table 2. According to the evaluation intended to confirm the decontamination capacities by radioactive cesium, the radioactivity is equal to 822.23 Bq / kg before the short decontamination test of 30 minutes. , and the radioactivity is equal to 388.09 Bq / kg after the decontamination test, and the decontamination capacity is equal to 52.8%.

In addition, according to a 24-hour long evaluation test to confirm the decontamination capacity, the radioactivity before the decontamination test is equal to 761.93 Bq / kg, and the radioactivity after the decontamination test is equal at 231.58 Bq / kg, and the decontamination capacity is equal to 69.6%. That is, it was found that the ratio of the absorption and separation value in 30 minutes / absorption and separation value in 24 hours (short-term elimination rate) reaches 75%. , 9%, and sufficient decontamination capacity is obtained even for a short period of about 30 minutes. It can be noted that the pulp after decontamination treatment is separated into incinerated fly ash and elution, thus making it possible to measure the radioactivity of the elution. It is found that the radioactivity of the elution has a value no greater than a detection limit. The data obtained are shown in Table 3. For Example 2, the decontaminant of radioactive material is obtained in a manner similar to Example 1, except for a point for which the spray pressure the injector-type spray drying device is set at 50 mmHg. The data obtained are shown in Table 1. With respect to the radioactive material decontamination agent obtained, the shape of the radioactive material extraction particle aggregate is observed using a SEM microscope. The SEM image is shown in Figure 3 (Figure 3A is an image with a magnification factor of 500, and Figure 3B is an image with a magnification factor of 20000). From FIG. 3, it is found that the radioactive material extraction particle aggregate of Example 2 has a spherical shape and has an irregular structure on its surface. Next, the laser diffraction type particle size distribution measurement is performed on the radioactive material extraction particle aggregate, and a result is plotted by "il" in FIG. of the particle size distribution of the radioactive material extraction particle aggregate of Example 2 shown in Figure 2, it is then calculated that the average aggregate diameter (diameter D50) is equal to 5, 1 kim, the (diameter D90) is equal to 9.8 μm, and the level of aggregate less than or equal to 10 μm is 91.1%. In addition, the value of the specific surface area obtained by the BET method is equal to 62.5 m 2 / g, and the value of the actual density is equal to 3.38. Then, with respect to the pore volume, the accumulated pore volume of the calculated aggregate is equal to 0.92 ml / g. In addition, the calculated cumulative pore volume is equal to 0.52 ml / g in a range not greater than the average diameter of the radioactive material extraction aggregate of Example 1 (the pore diameter is, in this example, 5.53 Inn), and in a range not smaller than the average longitudinal axis length of the magnetic particles that form the source of radioactive material removal particles (the pore diameter is 243 nm in this example). In addition, the integrated value of the effective pore area calculated by the pressurized process in mercury is 41.3 m 2 / g. In addition, the percent value of the [pore effective area per pressurized process in mercury / specific surface area obtained by the BET method] is 66.1%. The data obtained are shown in Table 2. According to the evaluation intended to confirm the decontamination capacities with radioactive cesium, the radioactivity is equal to 728.7 Bq / kg before the short 30-minute decontamination test, and the radioactivity is equal to 285.1 Bq / kg after the decontamination test, and the decontamination capacity is equal to 60.9%. In addition, according to a 24-hour long extraction test, the radioactivity is equal to 761.93 Bq / kg before the decontamination test, and the radioactivity is equal to 30 245.59 Bq / kg after the test. decontamination, and the decontamination capacity is 67.8%. That is, it was found that the ratio of the absorption and separation value in 30 minutes / absorption and separation value in 24 hours (extraction rate over a short period of time) ) reaches 89.8% and, similarly to Example 1, a sufficient decontamination capacity is observed even for a short time in a manner similar to Example 1. It can be noted that the paste after the decontamination treatment is separated into incinerated fly ash and an elution, thus measuring the radioactivity of the elution. It is found that the radioactivity of the elution has a value no greater than a detection limit. The data obtained are shown in Table 3.

For example 3, the decontaminant of radioactive material is obtained in a manner similar to Example 2, excluding a point for which the paste containing the particles of extraction of radioactive material and having a concentration of 5% of part solid, is used, and an undiluted solution feed rate of the spray dryer is adjusted to 17%, and the MR treatment is not carried out. The data obtained are shown in Table 1. With regard to the aggregate of radioactive material extraction particles contained in the radioactive material decontamination agent of Example 3, the average diameter of aggregate (diameter D50 ) measured is equal to 5.4 μm, the (diameter D90) measured is equal to 10.9 μm, and the level of aggregate less than or equal to 10 μm measured is equal to 87.1%. In addition, the specific surface area of the aggregate obtained by the BET method is equal to 58.7 m 2 / g, and the value of the actual density is equal to 3.18. Further, the SEM image of the resulting aggregate is shown in Fig. 4A with magnification corresponding to a magnification factor of 500 and in Fig. 4B with magnification corresponding to a magnification factor of 2000. In addition, a SEM image in section of the aggregate obtained (shown with an enlargement corresponding to a magnification factor of 15000) is shown in FIG. 5. As is evidenced from these images, the pores are present not only on the surface of the aggregate, but also within the aggregate. Then, the cumulative value of the pore volume of the calculated aggregate is equal to 0.84 ml / g. The cumulative calculated pore volume is equal to 0.48 ml / g in a range not greater than the average diameter of the aggregate of radioactive material extraction particles of Example 3 (the pore diameter is equal to 5, 53 gm in this example), and in a range not smaller than the average longitudinal axis length of the magnetic particles that form the source of radioactive material removal particles (the pore diameter is 243 nm in this example) . In addition, the value of the effective pore area calculated by the pressurized process in mercury is 23.0 m 2 / g. In addition, the percentage value of the pore effective area pressurized in mercury / specific surface area obtained by the method BET] is equal to 39.2%. The data obtained are shown in Table 2. According to the evaluation intended to confirm the decontamination capacities with radioactive cesium, the radioactivity is equal to 869.0 Bq / kg before the short 30-minute decontamination test, and the radioactivity is equal to 257.3 Bq / kg after the decontamination test, and the decontamination capacity is equal to 70.4%. In addition, according to a 24-hour long extraction test, the radioactivity is equal to 886.6 Bq / kg before the decontamination test, and the radioactivity is equal to 20 208.4 Bq / kg after the test. decontamination, and the decontamination capacity is equal to 76.5%. That is, it was found that the ratio of the absorption and separation value in 30 minutes / absorption and separation value in 24 hours (extraction rate over a short period) reaches 92 , 0%, and sufficient decontamination capacity exists even for a short time similarly to Examples 1 and 2. It can be noted that the pulp after the decontamination treatment is separated into incinerated fly ash and eluted , thus making it possible to measure the radioactivity of the elution. It is found that the radioactivity of the elution has a value no greater than a detection limit. The data obtained are shown in Table 3. In Comparative Example 1, 720 g of pure water are poured into the 1000 ml beaker, and 30 g of needle-shaped iron-cobalt alloy particles are added. having an average longitudinal axis length of 235 nm (cobalt / iron = 3.0 atomic%) produced by DOWA Electronics Corporation, are added internally as a source powder containing the magnetic particles. Then, a fast emulsification and dispersing machine (TK Mark II homogenizer mixer by Primix Corp.) was used to ensure the emulsification and dispersion of the source powder for 30 minutes at 8000 rpm. to obtain the source powder paste. 2.5 g of ammonia with a concentration of 21.3% are added to the source powder paste, thereby changing the pH for basic pH, and then 0.25 g of PDDA (39%). a solid part of polydimethyldiallylammonium chloride) is added to the latter, so that the magnetic particles are dispersed and emulsified at 8000 rpm for 30 minutes by the above-mentioned dispersion machine, so as to obtain the pulp of the magnetic particles. 82 g of aqueous potassium ferricyanide at 0.5 mol / l and 110 g of 0.49 mol / l aqueous nickel sulphate are respectively added to the paste obtained from magnetic particles bound to a coating layer, and Emulsification is continued for 30 minutes at 8000 rpm by the aforementioned dispersion machine 20 so that the nickel ferrocyanide adheres to the magnetic powder connected to the PDDA, so as to obtain the paste (concentration of about 5% the solid part) containing the radioactive material extraction particles. The resulting paste containing the radioactive material extracting particles is filtered by a hardened No. 5C filter paper without a spraying and drying operation, and is then dried under a nitrogen atmosphere for 24 hours at room temperature, so that thereby obtaining the aggregate of radioactive material extracting particles of Comparative Example 1. The data obtained are shown in Table 1. Disintegration treatment is applied to the aggregate of radioactive material extracting particles obtained. using an agate mortar under a nitrogen atmosphere, thereby obtaining the radioactive material decontaminating agent of Comparative Example 1. The radioactive material decontaminating agent obtained is sieved under atmospheric pressure. in order to distribute the particle size of the aggregates respectively in diameters of 40 to 63 gm. The form of the radioactive material decontamination agent obtained is observed using the scanning electron microscope. The observation is shown in Figure 6 (Figure 6A is an image with a magnification factor of 500, and Figure 6B is an image with a magnification factor of 5000).

From FIG. 4, it is shown that the radioactive material extraction particle aggregate of Comparative Example 1 has an intermediate shape and has an irregular structure on its surface. Next, a laser diffraction type particle size distribution measurement is performed on the radioactive material extraction particle aggregate, and a result thereof is plotted as "^" in Fig. 2. From the particle size distribution of the radioactive material extraction particle aggregate of Comparative Example 1 shown in Figure 2, it is shown that the average aggregate diameter (diameter D50) is equal to 19.4 1.1m, the (diameter D90) is equal to 52.0 kun, and the aggregate level less than or equal to 1.1m is equal to 31.6%. In addition, the value of the specific surface area obtained by the nitrogen adsorption process is equal to 67.5 m 2 / g, and the value of the actual density is 3.59. Then, with respect to the pore volume, the cumulative value of the pore volume of the calculated aggregate is 0.46 ml / g. The cumulative value of the pore volume in a range not greater than the average particle size of the radioactive material extraction aggregate of Comparative Example 1, (the pore diameter is 17.6 p, m in this example). Comparative Example 1), calculated is 0.29 ml / g. Further, the cumulative value of the pore volume is 0.28 ml / g in a range not greater than the average particle size of the radioactive material extraction aggregate of Comparative Example 1, and in a range of not less than the average longitudinal axis length of the magnetic particles which form the source of radioactive material removal particles (the pore diameter is 243 nm in this comparative example). In addition, the value of the effective pore area calculated by the pressurized process in mercury is equal to 25.3 m 2 / g. In addition, the percentage value of the pore effective area under pressure in mercury / specific surface area obtained by the process of BEI.] is 37.5%. The data obtained are shown in Table 2. In addition, the radioactivity is equal to 795.4 Bq / kg before the short decontamination test of 30 minutes, and the radioactivity is equal to 565.1 Bq / kg after the decontamination test, and the decontamination capacity is equal to 29.0%. According to a 24-hour evaluation test, the radioactivity before the decontamination test is equal to 761.93 Bq / kg, and the radioactivity after the decontamination test is equal to 269.15 Bq / kg, and the Decontamination capacity is equal to 64.7%. That is, it was found that the ratio of the absorption and separation value in 30 minutes / absorption and separation value in 24 hours (extraction rate over a short period) stabilizes at 44.8%. That is, it has been discovered that there is sufficient decontamination capability if long-term treatment can be applied to the liquid, but the decontamination capability is insufficient in the case of short-term decontamination operation. It can be noted that the paste, after the decontamination treatment, is separated into incinerated fly ash and an elution, and that the radioactivity of the elution is measured. Then, the radioactivity of the elution has a value no greater than a detection limit.

The data obtained are shown in Table 3. Table 1 Paste Spray Dry Operation Condition Concentration MR Treatment Filtering Inlet Temperature Spray Pressure Solid Feed Part Speed n (° C) (mmHg) (%) Example 1 10% Yes No 220 35 19 19 17 Example 2 10% Yes No 220 50 Example 3 5% No No 220 50 Example 5% No Filtering - - - Comparative 1 Table 2 Pore Volume Size Distribution Surface Specific Mercury Process / BET Combination Particle Method D50 D90 Inf. or Beach range BET process method equal to 10 total mercury specific im (I, im) (1m) (%) (ml / g) (ml / g) (m2ig) (m2ig) (%) Example 1 12.9 23.5 34.5 0.63 0.37 39.6 63.9 62 Example 2 5.1 9.8 91.1 0.92 0.52 41.3 62.5 66.1 Example 3 5.4 10.9 87.1 0.84 0.48 23 58.7 39.2 Example 19.4 52.0 31.6 0.46 0.29 25.3 67.5 37.5 Comparative 1 5 -37- Table 3 Extraction rate Extraction rate Short-term extraction rate (30 minutes) (24 hours) (%) (%) Coefficient of (%) Distribution coefficient distribution Example 1 52,8 1118,7 69, 6 2290.1 75.9 Example 2 60.9 1555.7 67.8 2102.4 89.8 Example 3 70.4 2377.9 76.5 3254.2 92 Example 29 407.5 64.7 1830.9 44.8 comparative 1 5

Claims (10)

REVENDICATIONS1. An aggregate of radioactive material extraction particles in which two or more radioactive material extraction particles comprising magnetic particles and a radioactive material adsorption component are associated, wherein a pore volume in the aggregate is greater than or equal to 0.5 ml / g and less than or equal to 5.0 ml / g, and the pore volume represents a cumulative value obtained by a process by pressurization in mercury. An aggregate of radioactive material extracting particles in which two or more radioactive material extraction particles comprising magnetic particles and a radioactive material adsorption component are associated, wherein a cumulative value of a radioactive material pore in the aggregate is greater than or equal to 0.3 ml / g and less than or equal to 3.0 ml / g in a range in which the diameter of the pore volume in the aggregate is greater than an average particle size of each magnetic particle which is a source of radioactive material extraction particles, and less than an average particle size of the aggregate, wherein the pore volume represents a cumulative value obtained by a pressurized process in mercury. 3. The radioactive material extraction particle aggregate according to claim 1, wherein a specific surface area of the aggregate obtained by the BET method (Brunauer, Emmett and Teller) is greater than or equal to 1 m2 / g and less than or equal to 400 m2 / g, wherein the BET method is the process of not performing a de-aeration operation. The radioactive material extraction particle aggregate according to any one of claims 1 to 3, wherein the average particle size (diameter D50) is greater than or equal to 0.1 μm and less than or equal to 100 μm. . The radioactive material extraction particle aggregate of any one of claims 1 to 4, wherein the radioactive material adsorption component is a ferrocyanide compound comprising at least one type of element. transition metal or group 12 elements. A method of producing an aggregate of radioactive material extracting particles, comprising the step of drying a pulp of a spray drying decontamination agent, wherein a metal salt of ferrocyanide-based compound is formed as a substance for extracting radioactive material on a surface of a magnetic particle with a layer of polymer or monomer formed on its surface by a wet process. A method of producing an aggregate of radioactive material extracting particles according to claim 6, comprising the steps of: forming the polymer or monomer layer on the magnetic particle by adding a polymer or monomer having cationic properties, to the paste in which the magnetic particles are dispersed; and forming a decontamination component on a coating layer and / or in the coating layer of the magnetic particles bound to a coating layer by adding the ferrocyanide compound having at least one type of the transition metal elements or Group 12 elements, to the paste of magnetic particles bonded to a coating layer. A process for producing an aggregate of radioactive material removal particles according to claim 6 or 7, wherein the spray drying is carried out by a spray dryer. 9. A process for extracting a contaminant, wherein the aggregate of radioactive material extraction particles according to any one of claims 1 to 5, is dispersed in a liquid to be treated containing a contaminant, so that the contaminant is displaced to the aggregate of radioactive material extraction particles. 10. A method of extracting a contaminant according to claim 9, wherein the decontamination material is radioactive cesium and / or radioactive thallium.